Vacuum system booster



Ap 2 1944- J. HULMAN ETAL V I I VACUUM" SYSTEM BOpsTER Originai Filed Aug 6, 1941 I Avvanvraes g/UL//S huz. MAN 552N420 5 ,4M4A/ Patented Apr. 25,1944

VACUUM SYSTEM BOOSTER Julius Hulman and Bernard Beaman,

Dayton, Ohio Original application August 6, 1941, Serial No. 405,673. Divided and this application January 5, 1942, Serial No. 425,678

(Granted under the m 01' March a, 1883, as

amended April 30, 1928; 370 0. G. 757) i 5 Claims.

The invention described herein may be manufacturedand used by or for Government for governmental purposes, without the payment to us of any royalty thereon.

This invention is a division of our co-pending application Serial No. 405,673, filed August 6, 1941, now Patent No. 2,301,096, of December 8, 1942, for a Fluid system pressure booster, and relates to a booster which is particularly applicable to a vacuum system whereina fluid is moved against a resistance.

The resistance may comprise no more than the friction encountered by the fluid in moving through the system, or it may include additional resistance, but in any event some pressure creating means is required at some part of the system to maintain flow. 1

Whatever the form that such pressure creating instrumentality may take, there will be a diiference in pressure, as between the upstream and downstream side thereof, in the system, such difference usually being greater as the resistance to be overcome is higher.

Such pressure difference is, of course, a function of a fluid system of this character, but there are many instances where the pressure drop on the low side is so great as to be highly objectionable.

It is therefore an object of this invention to provide means which may be incorporated in a fluid system of the general class above mentioned,

and which will have the effect of. raising th'e pressure at points where it may become undesirably low.

Another object is to provide a device of this kind which may be added to a conventional fluid system with little or no difliculty in installation.

Other objects and advantages and meritorious features will become evident as the following detailed description is read with reference to the drawing, wherein:

Figure 1 shows a conventional vacuum system used for maintaining a vacuum supply for operating vacuum motored instruments, etc. 7

Figure 2 shows how the subject matter of this invention may be of benefit when incorporated in a system as shown in Figure 3.

Systems for creating and maintaining a vacuum supply have numerous applications, and this is partciularly true in aircraft, where gyroscopes, cameras and other instruments are vacuum operated. A conventional vacuum system of this class is shown in Figure l, where the inlet 32 of a vacuum pump 34 is connected by pipes 36 and 38 ated. A vent l2 admits air to the instrument which passes through the pipes in the direction of the arrow 44, through the pump and out at 46, where it may be connected to and used for operating air pressure actuated equipment if so desired.

Inorder that the vacuum for operating the instrument 40 may be maintained at a desired value, a bleed type relief valve 48 is connected in the system between the instrument and the pump 34. This valve comprises a body having a suction opened valve disc 52 held on its seat by a spring 54, the stress of which is adjustable by the screw 56. A screen 56 prevents foreign matter from entering the valve. The screw 56 is adjusted so as to allow more or less of the pump's capacity to enter through the screen until the desired amount only flows through the instrument.

Figure 2 shows an improved vacuum system which operates with increased efliciency and greater economy by slight additions and rearrangement of parts. The same pump 34 has a discharge pipe 66 and inlet 32 connected by a pipe 35 to a venturi 60. The instrument I is vented at and connected by a pipe 62 to the throat of the venturi.

In lieu of the bleed type relief valve 46 of Figure 1, a throttling type valve 64 is provided. This valve comprises a body 66 with a small piston 66 slidable therein. A port I6 extends transversely through the piston, and an axial opening in its end contains a spring I2 which is biased to hold the piston to the position shown against a shoulder 14 formed in the body. The space at the end ofthe piston adjacent the shoulder H is connected tothe atmosphere by a vent 16, while the space at the end of the piston which contains the spring is connected by a small pipe 18 to the pipe 62. A screw 86 is pfovided for adjusting the stress of the spring 12. The improved vacuum system shown in Figure 4 operates as follows:

The pump 34 draws air in at the vent 42 of the instrument through pipes 62 and 35 to the pump inlet 32 and through the pump. No air P will be drawn through the air passage 82 at first because the transverse port 10 of the piston is misaligned with the passage. When vacuum in the pipe 62 has reached that value for which the screw is adjusted, the vacuum acting through the pipe 18 upon the end of the piston which contains the spring 12 will pull the piston to a posi tion where the port 10 and passage 82 are aligned, or sufliciently aligned to allow the excess capacity of the pump to be drawn in at the passage 82,

to the instrument 46 which is to be vacuum oper- 55 h ou h po 1 n u i and p pe 35. The

now through pipe 62 and passage .82 will .be in the direction of the arrows 84 andBGrespectively.

A screen .88 keeps foreign matter from .being- 7 drawn through the device.

The advantages of the improved-vacuum systemv shown in Figure 2 .will'be apparent. The

Ipressureat the Venturi throat, where the pipe "lzflenters and the amount of flow through the throat is fixedv by the requirement of the instrument 42, and the flow of air into the systern at 82 will depend of course on the amount. .of excess capacity of the pump, the pressure drop of the excess air being a function of the ratio of the excess'fiow to the required flow and willthereforebelower asthe ratio is'greater,

and due to the nature of a venturi, the pressure in the pipe 35 at the pump inlet 32 will be raised.

This in itself is'important, but there is another advantage, nameIy that while in .the conven tional system shown in Figure 1, the entire .capacity of the pump, boththa-t portion which enters through the screen 58 and that portion which .entersthrough the instrument 42, must be reduced to the vacuum required by the in- V the system at a higher pressure.

While one specific embodiment of the invention has been shown and described, and its superiority' noted, it 'will be apparent that the inventionimay be employed to goodadvantage in substantially any circulating fluid systemwhere it is desirable to raise the pressure on the low pressure side of the circuit, which willbe at the intake of the pressure producing means. This pressure rise is accomplished with little change in conventional practice and the necessary addition includes no moving parts, nor does it add to the power required to operate the system.

Throughout the specification and claims we have'used the word venturi," butit will be and said inlet, a passageway connecting said enclosure to the throat of said venturi, and means understood that this term is to be construed in its broader'sense to include any device having its passageway restricted at one part to cause increased rate of how and a consequent lowered pressure in the restricted part.

-So, also,-' the term throat when applied to a ered'pressure.

We claim:" 1. Avacuum system comprising, in combination, an enclosure within which a vacuum is to .means containing an opening connecting said.

containing an opening connecting the said passageway to the vacuum-openable valve to open 'tion, an enclosure within which a vacuum is to be created, a pump, means containing a duct from the atmosphere to the pump inlet, said means including a valve having vacuum-operative mechanism for varying the flow capacity of said duct and a venturi between said valve and said inlet, means containing a passageway from the atmosphere to the throat of the venturi, said'passageway passing in part through said enclosure, and means containing an opening connecting the vacuum-operative mechanism of the valve to the-said passageway for opening said valve. v

3. A vacuum system comprising, in combination, an enclosure within'which a vacuum is to be created, a pump, means adaptedto provide a duct leading from the atmosphere to the pump inlet, said means including a vacuum-openable valve and a venturi, said venturi being between said valve and said inlet, means containing a vacuum passageway for connecting said enclosure to the throat of said venturi, a piston in said valve operable by suction for opening said valve, means enclosing a vacuum chamber around one end of said piston, and means containing an opening connecting the vacuum passageway to said chamber.

4. The structure defined in claim 2 the piston is spring-biased to closed position.

5. A vacuum system comprising, in combination, an enclosure within which a vacuum is to becreated, a pump, means adapted to provide a .duct for connecting the inlet of said pump to the atmosphere, said means including a piston valve and a venturi, said venturi being located between said piston valve and said inlet, means containing a passagew .y for connecting said enclosure to the throat ofsaid venturi, a spring in said. valve at one end of said piston for urging said piston endwise to a closed position, and

passageway to the space in said valve at the said end of said piston.

JULIUS HULMAN. BERNARD BEAMAN.

wherein- 

